For a time after mass murders like that in an Aurora, Colo., movie theater on July 20 (and the even more recent killings at a Sikh temple in Oak Creek, Wis.), the public seeks causes and wants to know how the tragedy could have been prevented.

“Rampage violence seems to lead to repeated cycles of anguish, investigation, recrimination, and heated debate, with little real progress in prevention,” wrote John Harris, M.D., M.B.A., a clinical assistant professor of medicine in the College of Medicine, and Robin Harris, Ph.D., M.P.H., an associate professor of public health in the College of Public Health, at the University of Arizona, in the June American Journal of Public Health.

“These types of events can lead to despair about their inevitability and unpredictability,” they said in a prescient call for more and better research into the phenomenon.

Indeed, what leads someone to mass murder—officially, the deaths of at least four people in one incident?

Shootings like those at Aurora, Columbine, Virginia Tech, Oak Creek, and many more have been variously termed “rampage,” “autogenic,” or “pseudocommando” killings, the last a term coined by forensic psychiatrist Park Dietz, M.D., M.P.H., Ph.D., in a 1986 article.

Typically, the pseudocommandos are males who carefully plan their massacres, accumulate weapons and ammunition, dress as warriors in camouflage or body armor, and are prepared to die or be killed, wrote James Knoll IV, M.D., director of forensic psychiatry and an associate professor of psychiatry at SUNY Upstate Medical University in Syracuse, N.Y., in a pair of 2010 articles in the Journal of the American Academy of Psychiatry and the Law.

Knoll referred to a study of five pseudocommando murders by Paul Mullen, D.Sc., now a professor emeritus at Monash University in Melbourne, Australia.

Mullen concluded that these killers had several traits in common. The men were bullied or isolated as children and became loners as adults. They were suspicious, resentful, obsessional, narcissistic, and often paranoid.

“Via projection, such individuals perceive others as persecutory, as well as withholding the goodness and happiness to which they are entitled,” wrote Knoll. They feel rejected, hold grudges, and ruminate over perceived humiliations, eventually developing fantasies of violent revenge.

There are other views as well.

Journalist Dave Cullen spent years researching and writing a book about the Columbine massacre. He thinks the “loner” tag is just part of the conventional wisdom, for instance.

“[M]ost are not psychopaths …,” he wrote recently in the New York Times, urging against drawing conclusions about the Aurora massacre too quickly. “Far more often, they are suicidal and deeply depressed.”

A study of 91 “autogenic massacres” concluded that “typical perpetrators were low- or middle-status males with relatively low educational attainment and a history of relationship problems, and the trigger was a status loss or threat,” wrote Marissa Harrison, Ph.D., an assistant professor of psychology, and Thomas Bowers, Ph.D., an associate professor of psychology, in the School of Behavioral Sciences and Education at Pennsylvania State University, in the Journal of Forensic Psychiatry and Psychology in 2010.

In fact, gunmen at many of the recent shootings had all suffered long-or short-term reversals in school, work, or personal relationships.

Sometimes the public draws its own conclusions about causation, regardless of what research may indicate, said Donald Haider-Markel, Ph.D., a professor and chair of political science at the University of Kansas.

He studied national polls taken after the Virginia Tech (2007) and Tucson (2011) shootings and concluded that Republicans tended to place responsibility on the killer alone. Democrats were likely to focus on broader social conditions surrounding the tragedies, like breakdowns in the mental health system or access to weapons.

Since Aurora, there has been little discussion of gun laws—and none in the current presidential campaign—and more about mental illness, implying that there is “nothing anyone can do about it.”

“Support for gun ownership is at an all-time high now,” said Haider-Markel. “The Democrats are afraid to bring up the issue, especially in an election year, and the Republicans have them boxed in. At the same time, Republicans are not talking about ‘violence in the media’ because doing something about that would mean more government regulation, which they oppose, and Democrats are in favor of free speech.”

After the Virginia Tech shooting, some limitations were placed on gun purchases by those adjudged dangerous and mentally ill by a court, said Haider-Markel. “Otherwise, the greatest effect was on preparedness, such as using text messaging and other electronic communications to warn students to stay off campus during an incident.”

The other big question is whether such violent acts can be predicted and prevented.

Hindsight simplifies the answer.

“People look at events like this in retrospect, and the natural human tendency is to seek explanations,” said forensic psychiatrist Douglas Mossman, M.D., a professor at the University of Cincinnati, in an interview with Psychiatric News. “Post hoc, we see all kinds of warning signs that seem quite salient. A lot of ‘warning signs’ are ambiguous; most lead to nothing.”

Most of these explanations assume that the perpetrators were mentally ill. However, much research has shown that mental illness in the absence of substance abuse does not lead to violence and that most crimes are committed by people who have not been diagnosed with mental illness.

Even when behavior reaches a level troubling to family or neighbors, getting an affected individual into treatment is difficult, especially in a society that highly values individual liberty, said Mossman.

There are other barriers too—fewer public inpatient psychiatric beds, medication formulary restrictions, or fumbled handoffs from one link in the system to another.

Forensic psychiatry has advanced to the point where the probability of violence can be estimated about 70 percent to 80 percent of the time, wrote Mossman in a 2009 article in the Journal of Legal Medicine. But that isn’t accurate enough to rule out false positives in a random population sample or even among individuals with severe mental illness.

“Violence prediction alone may be a futile approach to reducing violence,” he wrote. However, treatment for people with mental illness would benefit patients and probably also reduce violence.

No matter how often they occur, too little is known about these mass killings, suggested Harris and Harris. More multidisciplinary, quantitative research, perhaps guided by an organization analogous to the National Transportation Safety Board and using tools like case-control studies, would better inform policy to prevent such tragedies.

Mossman, however, is skeptical of such reasoning.

“The proportion of people who are killed in rampage shootings is minuscule compared with the 30 to 40 people who die every day in the U.S. of homicide,” he said. “It troubles me that we focus on deaths in some shootings but not others. Maybe it could be the job of psychiatrists, who are specialists in understanding thought patterns, to point out to their fellow citizens why 99 percent of the other shootings in the U.S. go unremarked. What does that say about all of us?”

An abstract of “Rampage Violence Requires a New Type of Research” is posted at http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2011.300545?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed.